Answer: 17
Explanation:
Use the Pythagorean theorem.
C^2 = A^2 + B^2
So, C is always the hypotenuse which is the longest side length and the side length diagonal of the right angle. Side "s" is the hypotenuse.
Square sides AB and BD
It looks like this:
C^2 = 8^2 + 15^2
8^2 = 64
15^2 = 225
225 + 64 = 289
the square root of 289 is 17
17 = s